1. Field of the Invention
The present invention relates to a method for molding a film-covered article. More specifically, the invention relates to a method and apparatus that enables a stationary resin inlet to inject a plastic material behind a pre-molded flexible film.
2. Description of the Related Arts
It is known to manufacture molded articles by a method called in-mold film laminates. The method is described in U.S. Pat. No. 3,668,034 ('034). The '034 patent teaches placing a decorative laminate within a mold and then injection molding a polymeric material behind the laminate. The resin inlet is juxtaposed the laminate backing. The polymeric material heats, softens and finally fuses to the backing on the laminate.
There are several problems arising from injecting molten plastic from the cavity surface opposite the film decorative surface. Is it generally desirable to use a stationary cavity and a movable core. The part is retained on the core after molding and is easily removed when the press is opened. The resin inlet is preferably placed in the cavity. The resin inlet is almost always stationary because it is connected to an auger feeding molten plastic material. It is desirable to place the resin inlet in the cavity because the cavity has many fewer moving parts than the core and it is easier to remove the part from the core than from the cavity.
It is also possible to use edge gating to supply molten plastic behind the film. In edge gating, plastic is injected around the edge of the film either through the cavity or the core. Edge gating only allows the gate to be placed a short distance from the edge of the part. The central area of large parts is not reached by edge gating. Additionally, edge gating leave a substantial core plug that must be trimmed and removed from the runners by pins or other means. Extended lengths of edge gating are difficult to maintain and often require heated runners and gate valves.
Heretofore, in-mold film laminates have been manufactured using movable cavities and stationary cores as illustrated in U.S. Pat. No. 5,514,427 ('427). The '427 patent teaches a press having a stationary core. The resin inlet is placed within the core and injects molten plastic material behind the film. The '427 patent does not teach how the finished molded article is removed from the press. U.S. Pat. No. 5,599,608 similarly teaches a movable core having a resin inlet injecting plastic behind the film.
It is desirable to provide a method and apparatus for injecting molten plastic through the cavity. It is further desirable to provide a mold press for in-mold film laminates that retains the finished molded article on a moveable core. Finally, it is desirable to provide method for sealing the film and resin inlet so that molten plastic does not flow to the decorative surface of the film.
These deficiencies and problems are overcome by the present invention.